1. Field of Invention
The present invention relates generally to mass digital data storage systems. More particularly, the present invention relates to systems and methods for protecting the contents of a flash memory device.
2. Description of the Related Art
The use of non-volatile memory systems such as flash memory storage systems is increasing due to the compact physical size of such memory systems, and the ability for non-volatile, or flash, memory to be repetitively reprogrammed. The compact physical size of flash memory storage systems facilitates the use of such storage systems in devices which are becoming increasingly prevalent. Devices which use flash memory storage systems include, but are not limited to, digital cameras, digital camcorders, digital music players, handheld personal computers, and global positioning devices. The ability to repetitively reprogram non-volatile memory included in flash memory storage systems enables flash memory storage systems to be used and reused.
Information that is stored in flash memory may be overwritten when the flash memory is repetitively programmed. For example, information that is written or stored into a given flash memory cell may be overwritten when no available flash memory cells remaining within the flash memory. While overwriting information or data stored in flash memory may be acceptable in some situations, overwriting stored information may be unacceptable in other situations, particularly when the stored information is important or valuable.
In order to prevent data stored in the flash memory of a flash memory storage system such as a flash memory card from being accidentally or inadvertently overwritten, a physical mechanism may be implemented on the flash memory card to substantially prevent information from being stored on the flash memory if the physical mechanism is configured in an appropriate position. A typical mechanism that is used on flash memory cards to prevent the accidental erasure of information stored on the flash memory cards is a write-protect switch. A write-protect switch is typically arranged such that when the write protect switch is in a first position, data may be read from and written to memory in a flash memory card. When the write-protect switch is in a second position, while data may still be read from memory in a flash memory card, data may no longer be written to the memory.
FIG. 1a is a diagrammatic representation of a flash memory card which includes a write-protect switch. For ease of illustration, some features, e.g., input/output pins, have not been shown in FIG. 1a. A memory card 10, as for example a Secure Digital card, has an indentation area 14 on one side. A write-protect switch 12 is arranged to slide within indentation area 14. As shown in FIG. 1a, write-protect switch 12 is in a first position, i.e., a xe2x80x9cwritexe2x80x9d or xe2x80x9cwrite-enabledxe2x80x9d position. When write-protect switch 12 is in the first position, when memory card 10 is inserted in a reader, the reader may be used to write or store information onto memory card 10. FIG. 1b is a diagrammatic representation of memory card 10 with write-protect switch 12 positioned in a second position, i.e., a xe2x80x9cwrite-protectedxe2x80x9d position. In the second position, write-protect switch 12 is arranged to prevent data from being written onto memory card 10.
When memory card 10 is to be accessed by a host device, memory card 10 may be inserted into a reader or an adapter that is either a part of or is coupled to the host device. FIG. 2 is a diagrammatic representation of memory card 10, when memory card 10 is inserted into an adapter. An adapter 22 generally allows information to be read from the memory card. When memory card 10 is not write-protected, then adapter 22 also enables information to be written to memory card 10.
FIG. 3a is a block diagram representation of a memory card, e.g., memory card 10 of FIG. 1a, which is not write-protected and is inserted in an adapter, e.g., adapter 22 of FIG. 2. When write-protect switch 12 is in a write position, contacts 30 associated with adapter 22 make contact with write-protect switch 12. In other words, contacts 30 are effectively arranged to sense when write-protect switch 12 is positioned such that memory card 10 is configured for information to be written onto memory card 10. When contacts 30 are substantially in contact with write-protect switch 12, then adapter may be used to enable information to be written into memory associated with memory card 10.
When write-protect switch 12 is in a write-protected position when inserted into adapter 22, as shown in FIG. 3b, contacts 30 generally fail to come into contact with write-protect switch 12. If contacts 30 effectively do not contact write-protect switch 12, then adapter 22 may not be used to write information into memory associated with memory card 10. By way of example, a computing device which is coupled to adapter 22 may not write information into memory associated with memory card 10 if contacts 22 detect that memory card 10 is write-protected.
While the use of a write-protect switch on a memory card is generally effective in preventing information stored on the memory card from being inadvertently erased or overwritten, costs associated with fabricating write-protect switches as well as costs associated with installing write-protect switches on memory cards may be higher than desired. In addition, since a write-protect switch is typically arranged to slide between a write position and a write-protected position, the write-protect switch may be accidentally slid into a wrong position. For example, when a memory card which has a write-protect switch in a write-protected position is transported, the write-protect switch may be accidentally moved into a write position when contact with another object or surface causes the write-protect to slide. If the write-protect switch on a memory card is accidentally moved into a write position, and a user fails to notice that the memory card is no longer write-protected, then the user may inadvertently overwrite and, hence, lose information that was stored on the memory card. Losing information which was intended to be saved is generally undesirable, particularly when the information is either important or irreplaceable.
Therefore, what is needed is a relatively inexpensive write-protect mechanism which is not likely to be accidentally disengaged. That is, what is desired is a low-cost write-protect mechanism which is effective for write-protecting the contents of a memory card, and substantially may not be accidentally moved from a write-protect configuration to a write configuration.
The present invention relates to a system and a method for write-protecting the contents of a flash memory device. According to one aspect of the present invention, a memory storage device includes a memory, and interface, and a housing. The interface is coupled to the memory, and allows the device to communicate or interface with an external device. The housing is arranged around the memory, and includes a first section and a tab that is partially attached to the first section to enable data to be written onto the memory through the interface. The tab is arranged to be detached from the first section to substantially prevent the data from being written onto the memory through the interface. In one embodiment, when the tab is partially attached to the first section, the memory storage device is substantially write-enabled. In such an embodiment, when the tab is detached from the first section, the memory storage device is substantially write-protected.
A memory card which includes a write-protect tab enables the contents of memory within the memory card to be protected when the tab is detached. Incorporating a removable write-protect tab into a memory card is relatively inexpensive, when compared to incorporating a write-protect switch. Further, while a write-protect switch may be accidentally toggled or otherwise dislodged from a desired write-protected position, a write-protect tab which is partially attached to the body of a memory card and is arranged to be snapped off of the body substantially eliminates the possibility of accidentally enabling writing to occur on a memory card that is intended to remain write-protected. As such, the contents of the memory within the memory card may be protected with less likelihood of being accidentally erased or overwritten.
According to another embodiment of the present invention, a memory card includes a non-volatile memory, an input/output interface, and a housing. The input/output interface is in communication with the non-volatile memory, and enables the memory storage card to interface with an external device. The housing, which effectively houses the non-volatile memory, includes a body and a tab. The tab is partially attached to the body to enable the memory card to be write-enabled, and is arranged to be detached from the body to enable the memory card to be write-protected.
In one embodiment, when the memory card is interfaced with the external device, the external device makes contact with the tab to determine that data may be written onto the non-volatile memory. In another embodiment, when the tab is detached from the body and the memory card is interfaced with the external device, the external device identifies that the tab is not present. Identifying that the tab is not present may enable the external device to determine that data may not be written onto the non-volatile memory.
According to still another aspect of the present invention, a method for utilizing a memory storage device that has a memory includes storing a first bit into the memory and removing a portion of the memory storage device. Removing the portion of the memory storage device substantially prevents additional bits from being stored into the memory. In one embodiment, when the portion is removed, an indentation is substantially defined in the memory storage device. In such an embodiment, the indentation may be arranged to enable a reader to determine that additional bits are prevented from being stored into the memory when the reader is interfaced with the memory storage device.
These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings.